Stock Condition Surveys – Part 1 - A Client’s Perspective

Many Client organisations will not have the skills and resources available in-house and will therefore use external consultants for delivery of stock condition surveys due to their scale and complexity. The choice of consultant is fundamentally important to the success of the survey and clients should be very thorough in their selection and procurement processes

Source: Black Cat Building Surveys Ltd

For many years in my professional career I was responsible for advising, organising and managing numerous large stock condition surveys for a range of Local Authorities and Social Housing Providers. The prime motivation for the stock survey usually revolved around stock transfer, strategic planning related to asset management and business plans, or in the case of schools to follow a prescribed method such as the Department for Education and Skills Asset Management Strategy (now the Department for Education). My initial involvement would always involve helping each of the various clients to understand what they wanted (in most cases there was a lack of real understanding of was required), to set the scope of the surveys, to manage and co-ordinate large survey teams and to present the data in an understandable and usable way.

If you are currently planning for a stock condition survey or maybe you already have one in progress, then there are many different things you need to consider in order to try to ensure that the data collected and indeed the outputs are actually what you intend. I can think of numerous examples where Clients have had difficulty in managing/coping with the vast amount of data that is produced, and once received, they were not exactly sure what to do with it. Over recent years, technology has gone some way to addressing this as data can be collected and collated in ‘real time’ and there are a range of ‘off the shelf’ software packages that will analyse the data and produce all sorts of reports and charts, which are useful as long as the Client knows their output requirements. Therefore, a successful stock survey requires many months of planning and organising.  From a Client organisation perspective there needs to be well organised strategic approach establishing precisely what is required and importantly how this will be achieved. The information below identifies some key issues which should be considered:

Source: Homebuying Guide

What is the purpose of the Stock Survey? - A very simple question which often produces a variety of different answers. The answer to this will actually set the scope of the survey and will decide the outputs that are required so if there is a lack of clarity at this point then the whole process becomes confused. Therefore will the data be used to plan future work packages, if so, over what period of time? Will the data be used for strategic planning and be incorporated into a business plan? or maybe assessing current and future repairs and maintenance liabilities or consider statutory compliance or possibly a combination of these. These examples are not exhaustive, however demonstrate the wide range of possibilities that a stock condition survey could be used to achieve. It is only possible to move onto the next stage of the process once a Client/organisation can provide a clear answer to this question. Only then is it possible to start to look at the scope of the survey, the attributes to be recorded, the sample size (will this involve cloning?), the required outputs, deadlines and also the available budget (for the condition survey).

I remember one particular organisation I was advising, a Local Authority, who required a stock condition survey for their commercial building stock. This included a range of buildings such as community centres, libraries, leisure centres, offices and numerous other public buildings. In total this amounted to approximately 400 different buildings, so not a large stock survey, but challenging due to the diversity of the building stock. I became involved at a very early stage and it soon became clear that there were differences of opinion in respect of what was required to be achieved within the client organisation itself. One particular senior manager was insistent that the data collected should be used for strategic asset planning and also to assist much lower cost day to day maintenance. This manager was adamant that the survey should record things like door handles, hinges, taps, plugs, sealant etc. therefore taking the required attributes to a ‘micro level’. I highlighted the consequences of this approach in terms of the high cost of each survey due to the amount of time the surveyor would be on site, the difficulty in consistency of recorded information if you provide surveyors with too many choices, and also the limitations of the hardware at the time. In the end I was able to steer this particular client down a much more sensible road however this demonstrates some of the challenges that may be encountered, through lack of understanding and differences of opinion.

Choosing the right people - Many Client organisations will not have the skills and resources available in-house and will therefore use external consultants for delivery of stock condition surveys due to their scale and complexity. The choice of consultant is fundamentally important to the success of the survey and clients should be very thorough in their selection and procurement processes. Many consultants advertise their experience and skills in delivery of stock condition surveys, however there are some important factors that should be considered when selecting consultants for this type of work:

Resources – Based upon what you have detailed in your brief, what resources will the consultant provide to the project to ensure that the data collected will be appropriate and consistent and also achieve the deadline that you have set?  It is important to find out precisely who will be carrying out the surveys (ask for CV’s), and who will be responsible for managing/overseeing the survey. Consultants will usually calculate their fee based upon the amount of time they are likely to spend on the project and the level of staff that will be needed. For large stock surveys what tends to happen is that less experienced staff (newly qualified, or those undertaking professional qualification such as APC), are used for the bulk of the surveys and a more senior member of staff is used to oversee the project. This can work as long as the senior member of staff, undertakes robust quality assurance checks of the data being collected and undertakes continual training throughout the process with the surveyors to try to achieve consistency. The whole process can easily break down if a Consultant does not manage the process in this way and will lead to incorrect/inconsistent data being collected. This should never be allowed to happen and is something that a Client should explore during the procurement process.

Procurement – All Clients will have a budget available for a stock survey and in fact this is something that helps define the scope of the survey. If you want a Consultant to understand what you require, and you want a fee that is reflective of the services that they will provide then you must ensure that your brief is suitably detailed and clear. This probably sounds obvious, however I have prepared endless tenders for many different types of work, where the briefs provided are so vague or poorly written that it is difficult to understand exactly what the Client is looking for making reflective fee calculations very difficult.

Prior to tendering for the ‘main’ stock survey, my advice would be to invite a number of Consultants to tender for a ‘pilot survey’. This will enable each Consultant to demonstrate their resources and capabilities for a small number of surveys, as well as finding out what works, or maybe does not work, before ploughing on with the bulk of the surveys. This exercise could form the first part of the selection process, which should also be preceded by Consultant interviews. This may sound like a lengthy process; however, it is extremely important to appoint the right Consultant. This approach may well reduce the possibility of serious issues arising either during the survey process or when you come to rely on the data that has been collected.

Consultant’s Fee – Always analyse precisely what the Consultant has included with their fee.  If your tender documentation, including your survey brief are sufficiently detailed then the Consultant should have provided a fee to reflect what you have asked for. If not, and the Consultant has included their own ‘inclusions or interpretations’ then this will make the fee very difficult to compare with other tenders. This should not happen, as this could invalidate a tender, depending upon the method in which tenders were issued. In any event there needs to be a detailed tender analysis in order for a Client to satisfy themselves that the Consultant can provide precisely what they want for the fee they have provided. Never be tempted to look at the headline fee alone, as without looking you cannot know what (or what is not) included within that fee.

In my next article I will consider stock condition surveys from a Consultant’s viewpoint and provide some examples of how I used to manage large stock surveys.


Author: Gary O’Neill

Please feel free to share this article and other articles on this site with friends, family and colleagues who you think would be interested

Information/opinions posted on this site are the personal views of the author and should not be relied upon by any person or any third party without first seeking further professional advice. Also, please scroll down and read the copyright notice at the end of the blog.

Damp in Buildings – Part 2 – Condensation – How to reduce the risk!

There are a few very simple, but nevertheless very effective ways we can reduce the risk of condensation, just by simply being aware of some of the activities we would normally undertake without even thinking

Source: Homebuilding & Renovating

In order to understand how to reduce the risk of condensation it is important to first understand how it occurs. If you have not already done so I would recommend reading last week’s article, ‘How condensation occurs’, before going any further. You will then understand that the ‘ingredients’ necessary for condensation to occur are moisture vapour and cool surfaces, which are exacerbated by poor insulation, poor heating and poor ventilation. Cool surfaces could be present due to thermally inefficient walls and surfaces, particularly in older buildings. In fact there are a whole host of reasons why the internal surface temperature of the internal fabric of a building may be cool (walls, windows, ceilings etc.,) including poor maintenance of external walls, rising damp, penetrating damp due to leaking rainwater guttering or downpipes, leaking roofs, single glazed windows, poor weather sealing around openings and cold bridges, which are areas of the building fabric which are less thermally efficient than the surrounding construction.

To reduce the risk of condensation occurring there are two primary things we should consider. Firstly, dealing with the root cause of the condensation and secondly, looking at the way we use a building and trying to find ways of reducing the amount of moisture vapour we emit.

Source: Home Guides - SFGate

In order to rectify the problem, we first need to establish the cause. This is where you may need the advice of a Building Surveyor, who will be able to undertake a thorough inspection and establish which factors or combination of factors are contributing to the condensation. This is important because if you do not deal with ALL of the contributing factors, you may slow down the amount of condensation occurring, however you will not actually solve the problem.  For example you may decide to improve the heating system, but if you do not deal with the thermally inefficient walls, then all of that increased heat will just disappear through the walls, and will have a limited effect.  So depending on what is established as the cause, it may be necessary to increase the internal surface temperature of the walls by either insulating internally (dry lining) or externally (insulated render system), replacing windows (possibly double or triple glazing), improving ventilation (possibly a mechanical extractor fan) and upgrading the heating system. As you would imagine, this could become very expensive, which highlights why you may need the advice of a professional to ensure that the correct remedial measures are undertaken. All buildings are different and the way we use buildings will also be different, therefore we cannot assume that the cause of condensation and the remedial works required will be the same in every situation.

After dealing with the building itself we must also consider ways in which we can reduce the amount of moisture vapour we emit in buildings. Yes, our human behaviour can have a significant impact on reducing moisture vapour in a building. If we start to think about ways in which we use and occupy our buildings and either do thinks in different ways, or even stop doing them completely, we can significantly reduce the risk of condensation. The best thing of all is that a change of behaviour is absolutely free! There are a few very simple, but nevertheless very effective ways we can achieve this, just by simply being aware of some of the activities we would normally undertake without even thinking.

Showering/bathing, Washing and Cooking are activities that we cannot avoid however all produce large amounts of moisture vapour.  We undertake these activities on a day to day basis, however when showering/bathing, try to not leave the shower or bath taps running more than you need, switch them off as soon as you can. If you have extractor fans, ensure that they are working, adequately sized and switched on when needed. You should also ensure that trickle vents in windows are open and that air bricks are not blocked. Although it may be cold outside, when you are leaving the bathroom, open the window to let fresh air in, which will soon clear the moisture vapour by replacing the moisture laden air with new fresher dryer air which will prevent moisture vapour condensing on the walls and windows.

Source: Maxzi

If you are using a Tumble Dryer, ensure that it is vented to the outside. I have undertaken a number of previous inspections where I have seen the flexible tumble dryer vents extracting into a room, rather than outside. This was due to lack of thought of the location of the tumble dryer and a general lack of understanding on the part of the occupiers. Also, when Drying Clothes try to avoid placing them on top of radiators. This is usually done for convenience, however again produces large amounts of moisture vapour. Whenever possible washing should be dried outside, or if weather conditions do not permit this then consider using an appropriately vented tumble dryer, or maybe even a trip to the launderette.

When Cooking use an extractor hood if you have one above your cooker and keep lids on saucepans as much as you can.  Avoid using Bottled Gas and Paraffin Heaters these produce large amounts of moisture vapour.

Finally, but very importantly, try to ensure you have a regular flow of fresh air around your house/buildings. This effectively dries out any moisture vapour and prevents it reaching concentration levels where condensation may become an issue.  Granted, nobody wants to release all of that lovely heat from a building in the depths of winter, however, opening windows for a short period of time may result in the internal environment becoming temporarily cooler, but it will also significantly help to reduce the risk of condensation.

Hopefully, now that you know how condensation occurs you can start to thing about ways in which you can help to reduce the risk. In future articles I will discuss other forms of damp in buildings such as rising damp and penetrating damp.

Author: Gary O'Neill

Please feel free to share this article and other articles on this site with friends, family and colleagues who you think would be interested

Information/opinions posted on this site are the personal views of the author and should not be relied upon by any person or any third party without first seeking further professional advice. Also, please scroll down and read the copyright notice at the end of the blog.

Damp in Buildings – Part 1 – Condensation – How it Occurs

If left untreated condensation can become a significant problem so it is important that people understand how it occurs and how to deal with it. Due to the fact that condensation produces water/moisture it can also act as a catalyst for a number of other defects that can be found in buildings

Source: Bob's Heating & Air Conditioning

Most people will have seen damp in their homes in one form or another, and in fact damp is one of the most common problems encountered in houses.  Damp can manifest itself in a number of ways including ‘wet patches’ on surfaces, mould growth and sometimes a musty smell.  If left untreated damp can lead to deterioration of internal surfaces and finishes, provide a very unsightly appearance and in certain circumstances lead to health problems, particularly for vulnerable user groups such as the elderly, young children and those with respiratory conditions such as asthma.  There are a number of different types of damp that can occur in buildings including rising damp and penetrating damp, however for the purposes of this article I want to focus on condensation. 

In order to understand how we can deal with condensation it is important to first understand how it occurs.  All air contains a certain amount of ‘invisible’ water vapour. You may not realise it, but as a human beings we are emitting water vapour constantly, you may not see it but it really is happening. Water vapour is also emitted by the activities we undertake in the home including washing, cooking, drying clothes, using portable heaters such as calor gas etc.  Basically, there are large volumes of water vapour being emitted in your home and the amount of water vapour that is emitted is determined by the activities that we carry out and the number of people in your house at any particular time.  Condensation occurs when this water vapour comes into contact with cooler surfaces and the air no longer has the capacity to hold any more water vapour. In order to understand this we need to first understand relative humidity, which is a generally poorly understood term.

Source: Own

Relative humidity relates to the actual water vapour present in air to that which could be present and is routinely expressed as a percentage. The reason we refer to ‘relative’ humidity is because air has a varying ability to hold moisture vapour depending on temperature. Warm air can hold more water vapour than cold air. Once relative humidity reaches 100% it no longer has the ability to hold any more water vapour and it will start to condense on cooler surfaces (something referred to as ‘Dew Point’), which is the physical change into a liquid (condensation). 

As an example, think about your bathroom. When you have a bath or shower, large quantities of water vapour are produced.  Sometimes this will develop into a ‘fog/mist’ in the room until you open the window or turn on an extractor fan.  Have you ever noticed that you get water developing on your windows and walls? This is condensation. Have you ever wondered why this happens more readily on cold days, and in the warmer months it is hardly noticeable?  This is because the air in your bathroom on colder days has less capacity to hold moisture than the air in your bathroom during warmer temperatures (remember warm air can hold more water vapour than cold air). Windows, particularly in older buildings are generally less thermally efficient than the surrounding structure such as the walls. Therefore the internal surface temperature of the windows will be a few degrees cooler than the surface temperature of the walls.  This will mean that once dew point occurs (100% relative humidity), it will start to condense on the cooler surfaces first, i.e the windows, before it starts to condense on the surrounding walls.

Condensation can occur in any room in a house or within the structure of a house (interstitial condensation), including roof and floor voids, basically anywhere, where there is water vapour and cool surfaces. If left untreated condensation can become a significant problem so it is important that people understand how it occurs and how to deal with it. Due to the fact that condensation produces water/moisture it can also act as a catalyst for a number of other defects that can be found in buildings, namely timber decay such as wet rot or dry rot, as well as causing mould growth and potential health problems. 

You do not need to be a damp specialist or a building surveyor to be able to deal with condensation or at least reduce the risk of it occurring. There are numerous products on the market that claim to reduce or remove the risk of condensation in homes including paints and sprays.  These types of products may temporarily remove condensation mould that may have already occurred, or cover over damp mould, however the only certain way of removing the risk of condensation is to understand the root cause, which will vary from building to building, and to rectify these root causes.  The usual factors that result in condensation are poor thermal insulation, inadequate heating, inadequate ventilation and crucially, the way in which we use our homes, or a combination of these. In the next article I will explain how you can reduce the possibility of condensation in your home and if you already have problems with condensation I will tell you how to deal with it.

Author: Gary O'Neill

Please feel free to share this article and other articles on this site with colleagues, friends and family.

Information/opinions posted on this site are the personal views of the author and should not be relied upon by any person or any third party without first seeking further professional advice. Also, please scroll down and read the copyright notice at the end of the blog. 

Routine property maintenance – Why is it so often overlooked? – Part 1

By adopting a planned approach to maintenance an occupier can help to avoid the need for unplanned emergency repairs. This will also help to maintain the value of a building and in some cases even help to add value.  

Source: quotationcheck.com 

I am not a mechanic but like most people I am aware that if I do not do take care of my car then it will eventually break down. Regardless of what you may know about cars, most people can do basic things such as checking oil and water levels, checking and maintaining tyre pressures as well as the filling up with fuel and occasionally even cleaning your car!  In a similar way buildings require 'regular basic maintenance' in order to prevent more long term issues manifesting themselves, which if not carried out can prove to be very expensive to rectify. As a Chartered Building Surveyor it never ceased to amaze me when I would see significant defects or damage, which had resulted from what would have originally been a very simple thing to fix.  On occasions this was down to lack of knowledge or awareness on behalf of the occupier, however it can also be said that laziness was also a common cause. This is because many see and are aware of problems in their building but do not see any urgency as the building is still ‘functioning’. Basically, the issue is ignored!  Going back to the example of the car, it would be the same as hearing a rattling noise in your car as you drive along and instead of getting this rectified you turn the radio up, because the car is still  'functioning'. Eventually however the car will break down and the cost of repair is likely to be much more expensive than if you had dealt with the problem in the first place.  The old adage ‘prevention is better than cure’, is something that immediately comes to mind and this is particular relevant in respect of buildings.

By adopting a planned approach to maintenance an occupier can help to avoid the need for unplanned emergency repairs. This will also help to maintain the value of a building and in some cases even help to add value.  The value of a building can be significantly affected by its condition; in fact there are many examples of properties of similar size and type, in very close proximity that can vary by many thousands of pounds as a result of the difference in their conditions. If regular un-costly maintenance can add significant value to a property, then you would have to ask why so many people fail to do it!

Source: www.todayshomeowner.com

There are a number of routine basic maintenance tasks that can be undertaken in a building (both externally and internally) in order to increase the serviceable life of various components and to prevent more serious, often costly problems occurring in the future.  As you can see from my suggestions below, in most cases you do not need any specialist knowledge or training and you will only need to engage the services of a building contractor for the more risky or complicated activities or possibly where it may be more physically challenging than you are able.

Clear rainwater gutters - Blocked gutters will allow rainwater, sometimes in high volumes, to discharge onto external surfaces.  Over a period of time this can result in problems such as penetrating damp, condensation and timber decay to occur.  Large volumes of water discharging into the ground can also affect the ground bearing capacity of certain types of ground under foundations, sometimes resulting in very serious problems such as ground movement such as settlement or subsidence.  Therefore regularly checking that gutters are clear can prevent some very significant defects occurring in the future.

Cut back trees, shrubs and vegetation - Trees, shrubs and vegetation provide a much softer appearance than buildings and structures and are an important feature for many when considering purchasing or occupying a building.  Whereas they have many positive qualities, if not maintained they can prove to be extremely detrimental to a building.  Trees and particularly tree roots can undermine foundations and damage drains and are often found to be the cause or significant contributing factor to ground movement. Therefore, trees need to be monitored and maintained when they are located within a distance that could affect a building. If trees become an issue, specialist advice is likely to be necessary from an Arboriculturist in order to provide accurate remedial measures to address the problem.

Vegetation in close proximity to a building will retain a large amount of moisture.  Ivy is a common example of vegetation that grows rapidly and can cover large areas of external masonry walls.  Whilst this may provide a certain amount of ‘charm’ for many, in prolonged wet conditions, the ivy will retain a large amount of water, which will be in contact with external walls.  This will result in colder surface temperature for the wall, which in turn can increase the risk of condensation internally.  Add to this the fact that ivy provides a habitat for all sorts of insects which can use it as a route into window frames, air bricks and other weaknesses in the building at high level and suddenly it starts to lose a little bit of its charm. This is issue is not exclusive to ivy, in fact any vegetation that is allowed to grow in close proximity to a building has the potential to cause the same issues, and should therefore by regularly maintained and controlled.

Wash down UPVC  - Over the last thirty years UPVC has become increasingly popular as a material used for external building components, particularly for guttering and downpipes and window frames.  UPVC external cladding, soffits and fascia boards are also now commonly used in place of timber due to the perceived reduction in maintenance and improved life expectancy.  To a point this is correct, however it is a complete misconception that once UPVC is installed that it can be left forever and does not need any maintenance. Have you ever notice that when first installed that UPVC has a ‘shiny gloss’ finish.  However over a period of time being exposed to external elements, the surface will dull down. This can be due to photo-oxidation which causes bleaching (staining) and loss of pigmentation of the UPVC.  Once this occurs the UPVC will pick up dirt, dust and other particles and become discoloured.  Simply washing down UPVC surfaces every six months with warm soapy water will significantly reduce the risk of this occurring.
Next week, In part 2 I will discuss some further routine maintenance tasks that can be undertaken in a building (both externally and internally) in order to increase the serviceable life of various components and to prevent more serious, often costly problems occurring in the future.   

Please feel free to share this article and other articles on this site with friends, family and colleagues who you think would be interested

Information/opinions posted on this site are the personal views of the author and should not be relied upon by any person or any third party without first seeking further professional advice. Also, please scroll down and read the copyright notice at the end of the blog. 

Condensation in Buildings - Part 2 – How to reduce the risk!

There are a few very simple, but nevertheless very effective ways we can reduce the risk of condensation, just by simply being aware of some of the activities we would normally undertake without even thinking

Source: thevideo.biz

In order to understand how to reduce the risk of condensation it is important to first understand how it occurs. If you have not already done so I would recommend reading last week’s article (Link), ‘How condensation occurs’, before going any further. You will then understand that the ‘ingredients’ necessary for condensation to occur are moisture vapour and cold surfaces, which are exacerbated by poor heating and poor ventilation.  The cold surfaces could be present due to thermally inefficient walls and surfaces, particularly in older buildings.  In fact there are a whole host of reasons why the internal surface temperature of the internal fabric of a building may be cold (walls, windows, ceilings etc.,) including poor maintenance of external walls, rising damp, penetrating damp due to leaking rainwater guttering or downpipes, leaking roofs, single glazed windows, poor weather sealing around openings and cold bridges, which are areas of the building fabric which are less thermally efficient than the surrounding construction.

To reduce the risk of condensation occurring there are two things we should consider. Firstly, dealing with the cause of the condensation and secondly, looking at the way we use a building and trying to find ways of reducing the amount of moisture vapour we emit.

In order to rectify the problem, we first need to establish the cause. This is where you may need the advice of a Building Surveyor, who will be able to undertake a thorough inspection and establish which factors or combination of factors are contributing to the condensation. This is important because if you do not deal with ALL of the contributing factors, you may slow down the amount of condensation occurring, however you will not actually solve the problem. For example you may decide to improve the heating system, but if you do not deal with the thermally inefficient walls, then all of that increased heat will just disappear through the walls, and will have a limited effect. So depending on what is established as the cause, it may be necessary to increase the internal surface temperature of the walls by either insulating internally (dry lining) or externally (insulated render system), replacing windows, improving ventilation (possible a mechanical extractor fan) and upgrading the heating system. As you would imagine, this could become very expensive, which highlights why you may need the advice of a professional to ensure that the correct remedial measures are undertaken. All buildings are different and the way we use buildings will also be different, therefore we cannot assume that the cause of condensation and the remedial works required will be the same in every situation.

After dealing with the building we must also consider ways in which we can reduce the amount of moisture vapour we emit in buildings.   There are a few very simple, but nevertheless very effective ways we can achieve this, just by simply being aware of some of the activities we would normally undertake without even thinking.

Source: www.prokil.co.uk

Bathing, washing and cooking are activities that we cannot avoid however all produce large amounts of moisture vapour. We must undertake these activities on a day to day basis, however when showering/bathing, try to not leave the shower or bath taps running more than you need, switch them off as soon as you can.  If you have extractor fans, ensure that they are working, adequately sized and switched on when needed. Although it may be cold outside, when you are leaving the bathroom, open the window to let fresh air in, which will soon clear the moisture vapour and prevent it condensing on the walls and windows.

If you are using a tumble dryer ensure that it is vented to the outside.  I have undertaken a number of previous inspections where I have seen the flexible tumble dryer vents extracting into a room, rather than outside.  This was due to in both cases to lack of thought of the location of the tumble dryer and a general lack of understanding on the part of the occupiers. Also, when drying clothes try to avoid placing them on top of radiators.  This is usually done for convenience, however again produces large amounts of moisture vapour.  Whenever possible washing should be dried outside, or if weather conditions do not permit this then consider using an appropriately vented tumble dryer, or maybe a trip to the launderette.

When cooking use an extractor hood if you have one above your cooker and keep lids on saucepans as much as you can.  Avoid using bottled gas and paraffin heaters these produce large amounts of moisture vapour. 

Finally, but very importantly, try to ensure you have a regular flow of fresh air around your house/buildings.  This effectively dries out any moisture vapour and prevents it reaching concentration levels where condensation may become an issue.  Granted, nobody wants to release all of that lovely heat from a building in the depths of winter, however, opening windows for a short period of time may result in the internal environment becoming temporarily cooler, but it will also significantly help to reduce the risk of condensation.

Hopefully, now that you know how condensation occurs you can start to thing about ways in which you can help to reduce the risk.  In future articles I will discuss other forms of damp in buildings such as rising damp and penetrating damp.

Please feel free to share this article and other articles on this site with friends, family and colleagues who you think would be interested

Information/opinions posted on this site are the personal views of the author and should not be relied upon by any person or any third party without first seeking further professional advice. Also, please scroll down and read the copyright notice at the end of the blog.

Condensation in Buildings - Part 1 – How it occurs

If left untreated condensation can become a significant problem so it is important that people understand how it occurs and how to deal with it.  Due to the fact that condensation produces water/moisture it can also act as a catalyst for a number of other defects that can be found in buildings

Source: www.biocraft.co.uk

Most people will have seen damp in their homes in one form or another, and in fact damp is one of the most common problems encountered in houses.  Damp can manifest itself in a number of ways including ‘wet patches’ on surfaces, mould growth and sometimes a musty smell.  If left untreated damp can lead to deterioration of internal surfaces and finishes, provide a very unsightly appearance and in certain circumstances lead to health problems, particularly for vulnerable user groups such as the elderly, young children and those with respiratory conditions such as asthma. There are a number of different types of damp that can occur in buildings including rising damp and penetrating damp, however for the purposes of this article I want to focus on condensation.

In order to understand how we can deal with condensation it is important to first understand how it occurs.  All air contains a certain amount of ‘invisible’ water vapour.  You may not realise it, but as a human beings we are emitting water vapour constantly, you may not see it but it really is happening. Water vapour is also emitted by the activities we undertake in the home including washing, cooking, drying clothes, using portable heaters such as calor gas etc.  Basically, there are large volumes of water vapour being emitted in your home and the amount of water vapour that is emitted is determined by the activites that we carry out and the number of people in your house at any particular time.  Condensation occurs when this water vapour comes into contact with cold surfaces and the air no longer has the capacity to hold any more water vapour.  In order to understand this we need to first understand relative humidity, which is a generally poorly understood term.

Source:m.google.com

Relative humidity relates to the actual water vapour present in air to that which could be present and is routinely expressed as a percentage. The reason we refer to ‘relative’ humidity is because air has a varying ability to hold moisture vapour depending on temperature.  Warm air can hold more water vapour than cold air.  Once relative humidity reaches 100% it no longer has the ability to hold any more water vapour and it will start to condense on cooler surfaces (something referred to as ‘Dew Point’), which is the physical change into a liquid (condensation).

As an example, think about your bathroom.  When you have a bath or shower large quantities of water vapour are produced.  Sometimes this will develop into a ‘fog’ in the room until you open the window or turn on an extractor fan.  Have you ever noticed that you get water developing on your windows and walls?  This is condensation.  Have you ever wondered why this happens more readily on cold days, and in the warmer months it is hardly noticeable?  This is because the air in your bathroom on colder days has less capacity to hold moisture than the air in your bathroom during warmer temperatures (remember warm air can hold more water vapour than cold air).  Windows, particularly in older buildings are generally less thermally efficient than the surrounding structure such as the walls.  Therefore the internal surface temperature of the windows will be a few degrees cooler than the surface temperature of the walls.  This will mean that once dew point occurs (100% relative humidity), it will start to condense on the cooler surfaces first, i.e the windows, before it starts to condense on the surrounding walls.

Condensation can occur in any room in a house or within the structure of a house (interstitial condensation), including roof and floor voids, basically anywhere, where there is water vapour and cold surfaces.  If left untreated condensation can become a significant problem so it is important that people understand how it occurs and how to deal with it.  Due to the fact that condensation produces water/moisture it can also act as a catalyst for a number of other defects that can be found in buildings, namely timber decay such as wet rot or dry rot, as well as causing mould growth and potential health problems.

You do not need to be a damp specialist or building surveyor to be able to deal with condensation or at least reduce the risk of it occurring.  There are numerous products on the market that claim to reduce or remove the risk of condensation in homes including paints and sprays.  These types of products may temporarily remove condensation mould that may have already occurred, or cover over damp mould, however the only certain way of removing the risk of condensation is to understand the root cause, which will vary from building to building, and to rectify these root causes.  The usual factors that result in condensation are poor thermal insulation, inadequate heating and inadequate ventilation, or a combination of these.  In the next article I will explain how you can reduce the possibility of condensation in your home and if you already have problems with condensation I will tell you how to deal with it.

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Rising Damp – A Salty Problem - An update for 2015

Guest Article - Joe Malone - Principal: Malone Associates Ltd

My academic research into rising damp led me to the conclusion that most text books are wrong in their description of rising damp since they state that it is caused by capillary action.

Following on from my articles written in 2013 I thought it was time to provide a further update on one problem in particular relating to the diagnosis of rising damp. In my update for 2013 I wrote that, ‘you need to confirm that three conditions are present to definitively confirm a case of rising damp.’ These are:

1.  You must have a rising damp moisture profile. That is a profile that is wetter at the wall base but gradually decreases with height to a theoretical maximum height of circa 1.5m.

2.  You must prove that moisture is present at depth in the masonry and it is not enough to take surface readings from the plasterwork. You will need deep wall probes or a calcium carbide (speedy) meter to confirm this on site.

3.  You will need to confirm that nitrates are present in the damp apex of your moisture profile. This will involve doing on site analysis or sending a sample off to the labs. You might have noted that I've ignored chloride salts because these can be present in tap water or building materials. A positive test for nitrates confirms that the moisture has leached up from the soil.

My academic research into rising damp led me to the conclusion that most text books are wrong in their description of rising damp since they state that it is caused by capillary action. Since we know that the major moisture pathway for rising damp is the mortar perps and since we also know that the moisture transfer mechanism in mortar is diffusion then clearly the generally accepted cause by capillary action is incorrect. It is probably worth reprinting my own updated description at this point…

‘Rising damp is an upward migration of groundwater in masonry walls. It will act in combination on the masonry units and their separating mortar joints or it will act primarily on the mortar joints. The moisture transfer mechanism in masonry is capillary action whilst the moisture transfer mechanism within mortar is diffusion. The major moisture pathway for rising damp is the mortar perps so it can be stated that there are dual moisture transfer mechanisms for rising damp, diffusion and capillary action’

The purpose of this article is to right another wrong with regard to the academically accepted principle for salts analysis. If you note again the requirement to prove the third condition, the need to prove that Nitrates are present in the damp apex of your moisture profile. This requirement stems from the fact that Nitrates are present in the soil so if moisture is leached up from the soil then it stands to reason that the moisture contains Nitrates. Personally I have always used the chloride test very little since it has extremely limited value in the course of most damp investigations and it is a test that has always been of zero value for the diagnosis of rising damp, simply because we know that chlorides are present in tap water so a positive test for chlorides does not help us determine the source of moisture.

The Nitrates Anomaly

When testing for Nitrates we do so on the assumption  that Nitrates are not present in tap water and therefore a positive result moves us to conclude that moisture in the masonry has been drawn from the ground. I’m only aware of one salts analysis kit sold by Protimeter and indeed this is the one I use. Interestingly, Protimeter do not make their own salts analysis tablets and these are sourced from a company called Palintest.

Figure 1. Protimeter salts analysis kit.                   Source: surveyexpress.co.uk

However, we know that Nitrates can be present at very low levels. World Health Organisation guidelines stipulate a guideline for 50mg/l or less. So this raises a key question… Do we know that the tablets supplied by Palintest for the Protimeter salts analysis kit are discriminatory enough to only give a positive test result when  Nitrates levels are above and below 50 milligrams per litre? If not, then the source of moisture cannot be determined using this test since a positive result may also be obtained when the source of the wall base damp is a leaking incoming water main containing Nitrates at low levels of 50mg/l or less? If you have used the Protimeter kit you will know that a positive test for Nitrates turns the water cherry red and there is no colour chart to match against your sample to help determine the approximate quantity of Nitrates present. The practice of matching the sample colour obtained against a colour chart is a principle that may be familiar to a lot of freshwater fish enthusiasts since they have to regularly check Nitrate levels in their fish tanks to ensure levels do not become so high as to become dangerous for their fish.

Figure 2. Colour card familiar to freshwater fish keepers. Source: www.cichlid-forum.com

The Protimeter test for Nitrates appears to be less discriminatory than the test used by freshwater fish enthusiasts since it will turn cherry red and give a simple positive result with no clue as to the level of Nitrates present.

Figure 3. A positive nitrates test using Protimeter kit with Palintest tablets

I was uncomfortable with this and decided to contact the technical team at Palintest to ask them how discriminatory the Nitrates test was? They were incredibly helpful in providing the following response…

‘Your question is a good one.  I'm afraid you won't ever be able to be certain that the nitrates don't come from the tap water.  The test doesn't know the source of the water, it'll just react to any nitrates present.

You're also correct that the limit for nitrates is 50mg/l.

What I would recommend is to test the tap water on the site to test the 'baseline' nitrate level.  If your 'real test' is higher than this, you can be sure that some nitrate is coming from the rising damp.  If it’s less or equal to the baseline though, you aren't going to be able to tell.

You could expand your test protocol to include other minerals (sulphate, chloride etc) which would be able to give you some more confidence that the water is from the ground as opposed to the tap but you would need more equipment and would be a bit more complex than your current method.’

Before I even asked the question of Palintest I was already experimenting with a Nitrates test kit manufactured by Salifert. I chose this particular kit since I’d read on most forums that this was generally thought to be the most accurate kit. The kit is supplied with a colour match chart and is significantly cheaper than the Protimeter test kit.

Figure 4. Alternative Nitrates Test Kit  Source: Authors own

In fact I had been doing precisely what was recommended by Palintest… I was and am testing the tap water to establish a baseline Nitrates level according to my Salifert colour chart before I take a sample from the wall. The advice given by Palintest is good but of course ignores the issue relating to the absence of a colour chart in the Protimeter kit. It would seem that I was being advised to use another kit since the Protimeter kit can not discriminate and will simply, ‘just react to Nitrates present.’

In figure 5 you can see where I have obtained a positive test result for Nitrates at a level of around 25mg/l but this was for a tap water sample.

Figure 5. Positive nitrates test result in tap water.   Source: Authors Own

My trials and research with this alternative test method are still ongoing since rising damp is incredibly rare and to date I have only obtained negative results from walls and positive results from tap water.  I will need substantially more time to evaluate the effectiveness of my alternative Nitrates test but what is clear is that an alternative test is needed or some refinement is needed in the Nitrates test kit currently used by most building surveyors or damp investigators.  

Joe Malone - Principal: Malone Associates Ltd

First Published: 16/2/15 at   www.buildingdefectanalysis.co.uk

Please feel free to share this article and other articles on this site with friends, family and colleagues who you think would be interested

Information/opinions posted on this site are the personal views of the author and should not be relied upon by any person or any third party without first seeking further professional advice. Also, please scroll down and read the copyright notice at the end of the blog.